Metallated metal-organic frameworks

ABSTRACT

Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 14/333,792 that was filed Jul. 17, 2014, the entire contents ofwhich are hereby incorporated by reference. U.S. patent application Ser.No. 14/333,792 claims priority to U.S. provisional patent applicationNo. 61/857,314 that was filed Jul. 23, 2013, the entire contents ofwhich are hereby incorporated by reference.

REFERENCE TO GOVERNMENT RIGHTS

This invention was made with government support under contract numberDE-AC05-06OR23100 (Subcontract No. 10-20903 DOE, Oak Ridge, Tenn.)awarded by the Department of Energy. The government has certain rightsin the invention.

BACKGROUND

Metal-organic frameworks (MOFs) are a class of hybrid materialscomprising inorganic nodes and organic linkers. In many instancescoordinatively unsaturated metal sites—either at the linkers or thenodes—are essential for engendering desired functional behavior. Thesesites can facilitate catalysis, gas storage, and gas separation.

MOFs have been metal-functionalized from the condensed phase (i.e.,solution) either in de novo fashion or via post-synthesis modification.(See, Gordon, R. G.; Hausmann, D.; Kim, E.; Shepard, J. Chem. VaporDepos. 2003, 9, 73.) Unfortunately, considerable effort (in the form ofpurification and activation) is necessary to ensure that excess metals,and/or undesired solvent and other reagents, are removed fromsolution-metallated MOFs. Solvent molecules can also irreversibly ligateotherwise coordinatively unsaturated metal sites, yielding, in turn,less-than-desirable materials properties.

Meilikhov et al. demonstrated that a variety of metal inclusioncompounds (i.e., “metal@MOF” host-guest complexes) could be synthesizedutilizing chemical vapor infiltration from volatile metal complexesunder “sublimation-like” conditions. (See, Meilikhov, M.; Yusenko, K.;Esken, D.; Turner, S.; Van Tendeloo, G.; Fischer, R. A. Eur. J. Inorg.Chem. 2010, 3701.) However, little control can be obtained over thespatial distribution of the metal species within the MOF and, in someinstances, the resulting metal@MOF structures are unstable.

SUMMARY

Porous metal-organic frameworks , metallated porous metal-organicframeworks and methods of making and using them are provided.

The methods of metallating a porous metal-organic framework comprisedepositing a film comprising a metal on the surfaces within the pores ofthe metal-organic framework via atomic layer deposition. An example of aporous metal-organic framework suitable for metallation has the formulaZr₆ (μ₃-OH)₈(OH₈)(TBAPy)₂.

In some embodiments of the metallated metal-organic frameworks the metalfilm comprises catalytic sites. Such embodiments can be used to catalyzea reaction by exposing chemical reactants to the metallatedmetal-organic framework under conditions in which the metal filmcatalyzes the reaction.

In some embodiment of the metallated metal-organic frameworks the metalfilm comprises sorption sites. Such embodiments can be used inremediation applications by exposing a sample to the metallatedmetal-organic framework, whereby species in the sample are adsorbed orabsorbed at the sorption sites of the metallated metal-organicframework, and removing the metallated metal-organic framework andadsorbed or absorbed species from the sample.

Other principal features and advantages of the invention will becomeapparent to those skilled in the art upon review of the followingdrawings, the detailed description, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the invention will hereafter be describedwith reference to the accompanying drawings.

FIG. 1. An illustration of metallation by ALD in a MOF (AIM).

FIG. 2. Relevant structural features and representations of NU-1000. Forsimplicity hydrogen atoms are not shown.

FIG. 3. PXRD Patterns of NU-1000 simulated (Sim.), NU-1000 experimental(Exp.), Zn-AIM, and Al-AIM.

FIG. 4. DFT pore size distributions and N₂ adsorption isotherms (inset)for NU-1000, Zn-AIM, and Al-AIM.

FIG. 5. DRIFTS spectra for NU-1000, Zn-AIM and Al-AIM.

FIG. 6A. SEM-EDX images and spectra of NU-1000. FIG. 6B. SEM-EDX imagesand spectra of Zn-AIM. FIG. 6C. SEM-EDX images and spectra of andAl-AIM. The dashed line indicates where the EDX scan was taken.

FIG. 7. Residual electron density plots of the secondary frameworkobserved within the mesopores of NU-1000.

FIG. 8. A Zr₆-based node of NU-1000 comprising a staggered mixed protontopology with the molecular formula [Zr₆(μ₃-O)₄(μ₃-OH)₄(OH)₄(H₂O)₄]⁸⁺.

DETAILED DESCRIPTION

Porous MOFs and metallated porous MOFs are provided. Also provided aremethods of metallating the porous MOFs using atomic layer deposition andmethods of using the metallated MOFs as catalysts and in remediationapplications.

The MOFs have a structure comprising inorganic (e.g., metal) nodes, alsoreferred to as centers, coordinated via organic molecular linkers toform a highly connected porous network. The surfaces of the interiorpores of the MOF can be metallated using atomic layer deposition (ALD).ALD is a vapor-phase synthetic technique for depositing thin-films.Unlike other vapor-phase deposition techniques (e.g., chemical vapordeposition/infiltration) the precursor molecules in ALD deposit only atchemically reactive surface sites and do not react with themselves—thatis, the reactions are self-limiting. As a result, ALD can be used in alayer-by-layer film deposition process using cycle exposures ofprecursor molecules with intervening purge cycles. The process formetallating a MOF via ALD is referred to herein as AIM (metallation byALD in a MOF).

The MOFs used in the AIM process are desirably characterized by thefollowing properties: (1) they have mesoporous channels in order tofacilitate the diffusion of ALD reactants within the MOF; (2) they arethermally and hydrolytically stable at temperatures in the range from100-300° C.; and (3) the surfaces of their pores are functionalized withspatially oriented functional groups that are able to react with ALDprecursors to facilitate self-limiting film-forming reactions via ALD.As used herein, the term mesoporous refers to porous materials having anaverage pore size in the range from about 2 to about 50 nm. Methods ofmeasuring pore sizes are described in the example. Hydroxyl groups (—OH)are an example of a functional group that reacts with ALD precursormolecules. Other examples of suitable functional groups include water(H₂O), carboxylic acids (R—COOH), amine groups having a lone pair ofelectrons or a basic proton (e.g., ethylenediamine ortriethylenediamine), and base groups comprising one or more O, S, P or Catoms, such as those from sulfonic acid (R—SO₃H) and phosphonic acid(e.g., R—PO₃H).

Examples of MOFs having all of the above-referenced properties arezirconium MOFs constructed from hexa-Zr^(IV) nodes and tetratopiclinkers. Such MOFs are stable to 500° C., can contain mesoporouschannels and can contain spatially oriented —OH groups. (See, Cavka, J.H.; Jakobsen, S.; Olsbye, U.; Guillou, N.; Lamberti, C.; Bordiga, S.;Lillerud, K. P. J. Am. Chem. Soc. 2008, 130, 13850; Morris, W.;Volosskiy, B.; Demir, S.; Gándara, F.; McGrier, P. L.; Furukawa, H.;Cascio, D.; Stoddart, F. J.; Yaghi, O. M. Inorg. Chem. 2012, 51, 6443.)A specific example of a zirconium MOF that can be metallated using theAIM process has the molecular formula Zr₆(μ₃-OH)₈(OH)₈(TBAPy)₂ and thestructure shown in FIG. 2. This MOF is referred to herein as NU-1000.Alternative formulations of the structure of NU-1000 comprise oxo andaquo ligands in place of hydroxo ligands. Both of these alternativeformulations are capable of undergoing AIM to provide a metallated MOF.

Thus, for embodiments of the MOFs comprising aquo ligands, the molecularformula for the MOF can be described more generally as having nodesrepresented by the formula [Zr₆(μ₃-O)₈(O)₈(H₁₆)]⁸⁺ bridged bytetracarboxylate linkers. An example of a node comprising aquo ligandsin place of some hydroxo ligands is depicted in FIG. 8. This isomer ofthe node, comprises a staggered mixed proton topology with the formula[Zr₆(μ₃-O)₄(μ₃-OH)₄(OH)₄(H₂O)₄]⁸⁺.

A schematic diagram illustrating the AIM process is shown in FIG. 1,where the MOF structure is represented by a matrix of hexagonal pores.In this embodiment, the interior surfaces of the pores arefunctionalized by hydroxyl groups that react with a metal-containing ALDprecursor molecule, such as a metal-organic molecule, to provide a filmcomprising the metal on the surface of the pores. The ALD processillustrated in this figure uses cyclic exposures of trimethylaluminum,as the metal-containing precursor molecule, with a nitrogen purge cycle.

The films deposited within the pores of the MOF include films comprisinga single metal element and films comprising a plurality of metalelements, such as films comprising a binary combination of metalelements. Aluminum and zirconium are examples of metals that can bedeposited using ALD. Other metals that can be deposited include Mg, Si,Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Sr, Y, Nb, Mo,Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ba, La, Hf, Ta, W, Re, Os, Ir, and Pt.Moreover, although much of the present disclosure focuses on the use ofALD to form metal films, oxide films, such as metal oxide films, canalso be formed in the pores of the MOFs via ALD using, for example,repetitive metal-containing precursor/water exposure cycles.

The metallated MOFs can be used as catalysts for chemical reactions andin remediation applications. For example, some embodiments of themetallated MOFs comprise Lewis acidic sites that catalyze condensationreactions, as illustrated in the example below. Some embodiments of themetallated MOFs comprise sorption sites onto which species (e.g., metalelements, molecules or ions) from a sample (e.g., a vapor phase orliquid phase sample) are adsorbed or absorbed. For example, themetallated MOFs may be used for the capture of heavy toxic metals inwater remediation application, or to remove harmful chemical and/orbiological agents from the environment.

EXAMPLE

The example illustrates the synthesis and characterization of a Zr-basedMOF (NU-1000), as well as the use of NU-1000 as a platform forquantitative, self-limiting metallation by AIM.

Materials

All compounds and solvents: 1,3,6,8-Tetrabromopyrene (Aldrich, 97%),(4-(methoxycarbonyl)phenyl)boronic acid (Combi-Blocks, 98%), K₃PO₄(Aldrich), tetrakis(triphenylphosphine) palladium(0) (Strem Chemicals,99%), benzoic acid (Aldrich, 99.5%), ZrCl₄ (Aldrich, 99.5%),hydrochloric acid (Aldrich, 37%), neat diethylzinc (ZnEt₂) (Aldrich, Zn52 wt % minimum) and 1.1 M solution in toluene (Aldrich), neattrimethylaluminum (AlMe₃) (Aldrich, ≧36.3% Al) and 2.0 M solution intoluene (Aldrich), acetone (Macron, 98%), chloroform (BDH, 99.8%),1,4-dioxane (Aldrich, 99.8%, anhydrous), N,N-dimethylformamide (DMF)(Macron, 99.8%), tetrahydrofuran (THF) (Macron, 99.0%), deuteratedchloroform (d-CDCl₃) (Cambridge, 99.8%), deuterated dimethylsulfoxide(d₆-DMSO) (Cambridge, 99%), deuterated sulfuric acid (D₂SO₄) (Cambridge,96-98% solution in D₂O) were used as received without furtherpurification. n-pentane was dried on solvent still station before use.

Instrumentation.

¹H NMR spectra were recorded on a 500 MHz Varian INOVA spectrometer andreferenced to the residual solvent peak. Single crystals of NU-1000 weremounted in inert oil and transferred to the cold gas stream of a BrukerKappa APEX CCD area detector equipped with a CuKα microsource with MXoptics. Powder X-ray diffraction measurements were carried out on aBruker MX IμS microsource with Cu Kα radiation and an Apex II CCDdetector. The samples were mounted in capillaries as powders, sealedwith wax and placed on a goniometer head. The data were collected on anarea detector with rotation frames over 180° in φ and at 2θ values of12, 24, and 36° being exposed for 10 min at each frame. Overlappingsections of data were matched, and the resulting pattern was integratedusing Bruker's APEX2 phase ID program. The powder patterns were treatedfor amorphous background scatter. Optical images of NU-1000, crystalssynthesized out of DEF, were obtained using a Nikon SMZ1500 stereozoommicroscope coupled to a digital camera and PC (video monitor).Thermogravimetric analysis (TGA) was performed on a Mettler Toledo TGAunder N₂ flow and heated from room temperature to 700° C. (at 10°C./min). Metallation reactions by ALD were carried out in a Savanah S100system (Ultratech Cambridge Nanotech) under N₂. Inductively coupledplasma-optical emission spectroscopy (ICP-OES) data were collected onVarian Vista MPX instrument. Diffuse reflectance infrared spectra(DRIFTS) were recorded on a Nicolet 7600 FTIR spectrometer equipped withan MCT detector. The spectra were either collected under Ar atmosphere(samples loaded in a drybox under Ar) or in a KBr mixture under N₂ purge(samples prepared in atmosphere). In both instances KBr was utilized asthe background. N₂ adsorption isotherms were collected on either aTristar II 3020 (Micromeritics) or ASAP 2020 (Micromeritics). All poresize distributions were obtained using a carbon slit pore model with aN₂ kernel (Micromeritics). Scanning electron microscopy images andenergy dispersive spectroscopy profiles were collected on a Hitachi5-4800-II.

Synthesis of 1,3,6,8-tetrakis(p-benzoic acid)pyrene1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy).

1,3,6,8-tetrakis(4-(methoxycarbonyl)phenyl)pyrene. A mixture of(4-(methoxycarbonyl)phenyl)boronic acid (1.040 g, 5.80 mmol),1,3,6,8-tetrabromopyrene (0.500 g, 0.97 mmol),tetrakis(triphenylphosphine) palladium(0) (0.030 g 0.026 mmol), andpotassium tribasic phosphate (1.100 g, 5.30 mmol) in dry dioxane (20 mL)was loaded (in a glovebox) into a 20 mL microwave vial (Biotage) andcapped. This mixture was stirred under argon for 72 h at 130° C. in anoil bath. The reaction mixture was evaporated to dryness and the solidresidue was washed with water to remove inorganic salts. The insolublematerial was extracted with chloroform (three times by 50 mL), theextract was dried over magnesium sulfate, and the solvent volume wasreduced under vacuum. The residue was boiled in tetrahydrofuran for 2 hand filtered; the resulting filtrate contained mainly impurities. Thisprocedure gave 0.58 g of1,3,6,8-tetrakis(4-(methoxycarbonyl)phenyl)pyrene (82% yield).

¹H NMR (CDCl₃-d): δ 3.99 (s, 12H), 7.75 (d, 8H), 8.01 (s, 2H), 8.15 (s,4H), 8.23 (d, 8H).

1,3,6,8-tetrakis(p-benzoic acid)pyrene. To a 250 mL round bottom flaskcontaining 0.58 g (0.78 mmol) of solid1,3,6,8-tetrakis(4-(methoxycarbonyl)phenyl)pyrene, a solution containing1.5 g (37.5 mmol) NaOH in 100 mL of a THF/water (ratio 1:1) mixture wasadded and the resultant suspension was vigorously stirred under refluxovernight. The solvents were removed under vacuum and water was added tothe residue which formed a clear yellow solution. The clear yellowsolution was stirred at room temperature for 2 h and the pH value wasadjusted to 1 using concentrated HCl. The resulting yellow solid wascollected by filtration, and washed with water several times. The crudeproduct was recrystallized from DMF, filtered, washed with chloroformand dried under vacuum. This gave 0.49 g (91%) of the pure productH4TBAPy.

¹H NMR (DMSO-d₆): δ 7.86 (d, 8H), 8.09 (s, 2H), 8.17 (d, 8H), 8.21 (s,4H), 13.12 (s, 4H).

Synthesis of Zr₆(μ₃-OH)₈(OH)₈(TBAPy)₂ (NU-1000).

Synthesis of NU-1000 in DEF. 70 mg of ZrCl₄ (0.30 mmol) and 2700 mg (22mmol) of benzoic acid were mixed in 8 mL of DEF (in a 6-dram vial) andultrasonically dissolved. The clear solution was incubated in an oven at80° C. for 1 h. After cooling down to room temperature 40 mg (0.06 mmol)of H₄TBAPy was added to this solution and the mixture was sonicated for20 min. The yellow suspension was heated in an oven at 120° C. for 48 h.After cooling down to room temperature, yellow single crystals werepresent on the vial walls. The sample was washed with DMF andsubsequently activated with HCl, as described below.

Synthesis of NU-1000 in DMF. 70 mg of ZrCl₄ (0.30 mmol) and 2700 mg (22mmol) of benzoic acid were mixed in 8 mL of DMF (in a 6-dram vial) andultrasonically dissolved. The clear solution was incubated in an oven at80° C. for 1 h. After cooling down to room temperature 40 mg (0.06 mmol)of H₄TBAPy was added to this solution and the mixture was sonicated for20 min. The yellow suspension was heated in an oven at 120° C. for 48 h.After cooling down to room temperature, yellow polycrystalline materialwas isolated by filtration (35 mg of activated material, 54% yield) andwashed with DMF and subsequently activated with HCl, as described below.

Elemental analysis data for molecular formula Zr₆(OH)₈(TBAPy)₂(benzoicacid)₄: C, H, N, Cl Theoretical: 55.6%, 2.1%, 0%, 0%; Experimental:53.8%, 3.1%, 0.1%, 0.4%. Elemental analysis data for molecular formula{0.75*[Zr₆(OH)₈(TBAPy)₂(benzoic acid)₄]+0.25·[Zr₆(O)₄(OH)₄]₂(TBAPy)₆]}:C, H, N, Cl Theoretical: 56.4%, 2.2%, 0%, 0%; Experimental: 53.8%, 3.1%,0.1%, 0.4%.

Activation Procedure for NU-1000.

As synthesized NU-1000 was activated using a slightly modified methodpreviously reported by Feng et al. (See, Feng, D.; Gu, Z.-Y.; Li, J.-R.;Jiang, H.-L.; Wei, Z.; Zhou, H.-C. Angew. Chem. Int. Ed. 2012, 51,10307.) Approximately 40 mg of solvated (“wet”) material was soaked in12 ml of DMF and 0.5 ml of 8 M aqueous HCl was added.

This mixture was heated in an oven at 100° C. for 24 h. After cooling toroom temperature, the solution was removed and the material was washedtwice with DMF to remove HCl impurities. Subsequently the solid residuewas washed twice with acetone and soaked in acetone for additional 12 h.NU-1000 was filtered, briefly dried on a filter paper and activated at120° C. under vacuum for 12 h on the preparation station of ASAP 2020instrument. Shown below, the as synthesized NU-1000 sample wascharacterized by ¹H NMR, N₂ adsorption measurements, and DRIFTS. Thedata are consistent with the removal of benzoic acid from the Zr₆ nodeand the incorporation of —OH groups.

Elemental analysis data for molecular formula Zr₆(OH)₈(TBAPy)₂: C, H, N,Cl Theoretical: 48.7%, 2.4%, 0%, 0%; Experimental: 49.1%, 3.0%, 0.3%,0.4%. Elemental analysis data for molecular formula{0.75·[Zr₆(OH)₈(TBAPy)₂]+0.25·[Zr₆(O)₄(OH)₄]₂(TBAPy)₆]}: C, H, N, ClTheoretical: 51.6%, 2.5%, 0%, 0%; Experimental: 49.1%, 3%, 0.3%, 0.4%.

Synthesis of Zn-AIM and Al-AIM by ALD.

Approximately 20-30 mg of NU-1000 was loaded into a home built stainlesssteel powder holder and subsequently placed into a ALD reactor. NU-1000was allowed to equilibrate in the reactor for 0.5 h prior to the ALDdeposition. The ALD reactions were carried out utilizing the followingtiming sequence (time in s): t₁-t₂-t₃, where t₁ is the precursor pulsetime, t₂ the precursor exposure time (i.e., the time where the precursoris in contact with NU-1000 without pumping), and t₃ the N₂ purge time.ZnEt₂ was deposited at 140° C. utilizing five 1-120-120 sequences andAlMe₃ was deposited at 120° C. utilizing twenty 0.015-1-1 sequences.During t₁ and t₂ the N₂ flow rate was 5 sccm, while during t₃ the N₂flow rate was 20 sccm.

Synthesis of Zn-NU-1000 and Al-NU-1000 from Solution.

Zn-NU-1000. In a glovebox, 30 mg (0.014 mmol) of activated NU-1000 wasloaded into a 5 mL microwave vial (Biotage) and 4.0 mL of 1.1 M (4.4mmol, ca. 20-fold excess per —OH group in NU-1000) ZnEt₂ in toluene wasadded. The vial was capped and left for 24 h at room temperature. Thesolution was removed and the remaining yellow solid was washed once withn-pentane and left soaked in 5 mL of pentane for additional 24 h to washout unreacted ZnEt₂. Briefly dried Zn-NU-1000 was transferred in aglovebox to a Tristar sample tube and activated under vacuum on ASAP2020 at 120° C. for 12 h. Approximately 2 mg of activated Zn-NU-1000 wasexposed to air and digested in d₆-DMSO/D₂SO₄ mixture for ¹H NMRanalysis.

Al-NU-1000. In a glovebox, 30 mg (0.014 mmol) of activated NU-1000 wasloaded into a 5 mL microwave vial (Biotage) and 2.2 mL of 2 M (4.4 mmol)AlMe₃ in toluene was added dropwise. During addition of theorganometallic compound intense gas evolution was observed and after fewminutes initially yellow powder of NU-1000 turned orange. The vial wascapped and left for 24 h at room temperature. The solution was removedand the remaining solid was washed once with n-pentane and left soakedin 5 mL of pentane for additional 24 h to wash out unreacted AlMe₃.Briefly dried Al-NU-1000 was transferred in a glovebox to a Tristarsample tube and activated under vacuum on ASAP 2020 at 120° C. for 12 h.Approximately 2 mg of activated Al-NU-1000 was exposed to air anddigested in d₆-DMSO/D₂SO₄ mixture for ¹H NMR analysis.

Single Crystal X-Ray Structure of NU-1000 (from DEF).

Single crystals of C₈₈H₄₄O₃₂Zr₆ (NU-1000) were obtained from DEF,mounted in inert oil, and transferred to the cold gas stream of a BrukerKappa APEX CCD area detector equipped with a CuKα microsource with MXoptics.

NU-1000 Residual Electron Density Plots

During the structure refinement of NU-1000 the presence of a partiallyoccupied, and disordered, framework within the mesopores of NU-1000 wasobserved. The residual electron density showed evidence of a disorderednode and ligands. The essence of this secondary framework was capturedin residual electron density plots (FIG. 7), which based on the Q peakswas estimated to be present in ˜20% of the mesopores of NU-1000.

ICP-OES Analysis.

Approximately 2 mg of sample (e.g., Zn-AIM) was weighed out on a TGAbalance. The powder was transferred to a microwave vial (4 mL) and 0.25mL concentrated H₂O₂ and 0.75 mL concentrated H₂SO₄ were added. The vialwas capped and irradiated in a microwave oven at 150° C. for 5 min. Theresultant clear solution was diluted to 25 mL with nanopure water andanalyzed via ICP-OES. Zn and Al concentrations were calculated fromexternal stock solutions and compared to the known Zr content of theMOF.

Volumetric Isotherms for NU-1000, Zn-AIM, and Al-AIM.

Volumetric isotherms were calculated by using the metal loading,determined by ICP-OES, in Table 1. It was assumed that —Zn(C₂H₅) and—Al(CH₃)₂ were bound to the —OH groups of the Zr₆ nodes (i.e., thefollowing stoichiometry was assumed Zn(C₂H₅)₂+Zr—OH→ZrO—Zn(C₂H₅) andAl(CH₃)₃+Zr—OH→ZrO—Al(CH₃)₂). The crystallographically predicteddensities of 0.49 cc/g for NU-1000, 0.55 cc/g for Zn-AIM, and 0.59 cc/gfor Al-AIM were used.

Results.

Solvothermal reactions of ZrCl₄, 1,3,6,8-tetrakis(p-benzoic acid)pyrene(H₄TBAPy), and benzoic acid in diethylformamide (DEF) yielded crystalssuitable for single-crystal X-ray analysis. (See, Stylianou, K. C.;Heck, R.; Chong, S. Y.; Bacsa, J.; Jones, J. T. A.; Khimyak, Y. Z.;Bradshaw, D.; Rosseinsky, M. J. J. Am. Chem. Soc. 2010, 132, 4119;Stylianou, K. C.; Rabone, J.; Chong, S. Y.; Heck, R.; Armstrong, J.;Wiper, P. V.; Jeffs, K. E.; Zlatogorsky, S.; Bacsa, J.; McLennan, A. G.;Ireland, C. P.; Khimyak, Y. Z.; Thomas, K. M.; Bradshaw, D.; Rosseinsky,M. J. J. Am. Chem. Soc. 2012, 134, 20466.) The parent-framework node wascomposed of an octahedral Zr₆ cluster capped by eight μ₃-OH ligands.Eight of the twelve octahedral edges are connected to TBAPy units, whilethe remaining Zr coordination sites (after activation) are occupied byeight terminal —OH ligands. The 3-D structure can be described as 2-DKagome sheets linked by TBAPy ligands. Four of the eight terminal —OHgroups point into the mesoporous channels, while the remaining terminalhydroxyls lie in smaller apertures between the Kagome sheets. Theresultant MOF (FIG. 2) has the molecular formulaZr₆(μ₃-OH)₈(OH)₈(TBAPy)₂, which we have designated NU-1000. We observethat ˜20-25% of the mesoporous channels contain a secondary structuralelement based on residual electron density plots and N₂ adsorptionsimulations. We modeled the secondary element as[Zr₆(μ₃-O)₄(μ₃-OH)₄]₂(TBAPy)₆ which connects to twelve Zr₆ nodes of theparent framework through six TBAPy ligands. Finally NU-1000 wasactivated with a HCl/N,N-dimethylformamide (DMF) mixture similar to theprocedure of Feng et al. (See, Feng, D.; Gu, Z.-Y.; Li, J.-R.; Jiang,H.-L.; Wei, Z.; Zhou, H.-C. Angew. Chem. Int. Ed. 2012, 51, 10307.) ¹HNMR and diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) reveal that HCl removes benzoic acid from the Zr₆ nodes,leaving behind terminal —OH groups.

We initiated AIM (vide infra) with a microcrystalline powder of NU-1000,reasoning that this form would facilitate diffusion of ALD precursorswithin the MOF. The microcrystalline powder was obtained by switching toDMF as a synthesis solvent. The powder X-ray diffraction (PXRD) patternsof the DEF (simulated) and DMF prepared samples are identical and Pawleyrefinement of the DMF pattern demonstrates that the unit cell andsymmetry are identical as well. The remainder of this example willdiscuss DMF prepared samples only.

The N₂ adsorption isotherm of NU-1000 is best described as type IVc(FIG. 4); NU-1000 has a Brunauer-Emmett-Teller (BET) surface area of2320 m² g⁻¹ and a total pore volume of 1.4 cm³ g⁻¹. The experimentallymeasured surface area and total pore volumes are in excellent agreementwith the theoretical values of 2280 m² g⁻¹ and 1.4 cm³ g⁻¹ obtained fromgrand canonical Monte Carlo simulations (GCMC) and subsequent BETanalysis. DFT analyzed pore-size distributions indicate pores ofdiameter at ˜12 Å and 30 Å, consistent, respectively, with thetriangular micropores and hexagonal mesopores of NU-1000. Thermalgravimetric analysis (TGA) of a sample activated at 120° C. demonstratedthat NU-1000 is stable up to 500° C. The presence of —OH groups wasconfirmed by DRIFTS. Sharp peaks appear at wavenumbers 3674 and 3655cm⁻¹ (black curve in FIG. 4), which we have assigned to the terminal andbridging —OH stretches of the Zr₆(μ₃-OH)₈(OH)₈ node. TGA andtemperature-dependent-DRIFTS data are also quantitatively consistentwith the assigned —OH content of NU-1000. In addition, thetemperature-dependent DRIFTS data demonstrate that the —OH functionalitypersists under the conditions of our ALD experiments (vide infra).

Microcrystalline samples of NU-1000 were placed in an ALD reactor at140° C. or 110° C. and exposed to diethylzinc (ZnEt₂) or AlMe₃. The ALDreactions were carried out with the following timing sequence (inseconds): t₁-t₂-t₃, where t₁ is the precursor pulse time, t₂ theprecursor exposure time, and t₃ the N₂ purge time. Metallation wasconfirmed via inductively coupled plasma-optical emission spectroscopy(ICP-OES). The resultant materials have been termed Zn-AIM and Al-AIMfor Zn- and Al-Atomic layer deposition In a MOF. On average we observe0.5 Zn or 1.4 Al atoms per Zr atom, Table 1. These values correspond tothree Zn, or eight Al, atoms for every Zr₆ node in NU-1000. Consistentwith ALD-like behavior, longer exposure times, via repeated precursorexposure, did not lead to greater metal loading. To ascertain whether wewere fully accessing NU-1000 under our ALD conditions, we extendedexposure times to several hours, rather than seconds, by immersingsamples in solutions containing ZnEt₂ or AlMe₃ (Table 1, Zn-NU-1000 andAl-NU-1000). The loadings obtained through extended solution-phaseexposure are only slightly higher than those from transient ALD.

TABLE 1 ICP-OES, BET Surface Areas, and Pore Volumes for NU-1000,Zn-AIM, Al-AIM, Zn-NU-1000, and Al-NU-1000. BET Surface Pore Volume MOFMetal: Zr Metal: Zr₆ Area (m² g⁻¹) (cm³ g⁻¹) NU-1000 — — 2320 1.4Zn-AIM^(a) 0.5 3.0 1580 0.9 Al-AIM^(b) 1.4 8.1 1160 0.7 Zn-NU-1000 0.63.6 1710 1.0 Al-NU-1000 1.7 10.0 1290 0.7 ^(a)t₁ = 1 s, t₂ = 120 s, t₃ =120 s ^(b)t₁ = 0.015 s, t₂ = 1 s, t₃ = 1 s.

PXRD measurements (FIG. 3) showed that both Zn-AIM and Al-AIM retaintheir crystallinity. BET analyses of the N₂ adsorption isotherms (FIG.4) indicate a decrease in surface area from 2230 m²/g for NU-1000, to1580 and 1160 m²/g for Zn-AIM and Al-AIM. The gravimetric and volumetricsurface areas, along with total pore volumes, decrease with increasingmetal loading (Table 1). DFT pore-size distributions (FIG. 4), extractedfrom the N₂ isotherms, indicate that the average diameter of themesopore shifts from ˜30 Å in NU-1000 to ˜27 Å for both Zn-AIM andAl-AIM.

DRIFTS measurements (FIG. 5) confirmed that metallation occurs byreaction with —OH groups. Clearly the sharp peaks at 3674 cm⁻¹ and 3655cm⁻¹ have been significantly or completely reduced. The DRIFTS datasuggest that ZnEt₂ is able to react with —OH groups pointing into thelarge hexagonal channels, while AlMe₃ reacts with all terminal —OHgroups. To assess Zn and Al incorporation by individual MOFmicrocrystallites, we turned to scanning electron microscopy-energydispersive X-ray spectroscopy (SEM-EDX). As shown in FIG. 6A, only Zr(upper trace) was detected in NU-1000; Zn (lowest trace) and Al (middletrace) do not rise above the baseline. The blue line indicates where,spatially in the image, the EDX scan was performed over. When scanningZn- and Al-AIM (FIGS. 6B and 6C), Zn (lower trace) and Al (lightertrace) were detected throughout the entire NU-1000 crystal.

To demonstrate that AIM could be utilized to elicit new functionalbehavior we turned to chemical catalysis. The Knoevenagel condensationbetween ethyl cyanoacetate and benzaldehyde can be catalyzed by Lewisacids, albeit in limited scope and conversion rate. (See, Cui, H.-F.;Dong, K.-Y.; Zhang, G.-W.; Wang, L.; Ma, J.-A. Chem. Commun. 2007,2284.) The Zr^(IV) sites in NU-1000 proved inactive towards theKnoevenagel condensation. In contrast, Zn-AIM and Al-AIM were activecatalysts, which we attribute to the presence of Lewis acidic Al^(III)and Zn^(II) sites in Zn- and Al-AIM. While AIM, as implemented here,leaves methyl or ethyl ligand(s) on the incorporated metal ions, theseare highly reactive and will be removed and released as methane orethane shortly after exposure to benzaldehyde. After catalysis, thesolutions were filtered to remove the MOF and examined by ICP-OES;consistent with the assignment of Zn- and Al-AIM as the catalysts, no Znor Al was found in solution. The results demonstrate the potential forALD to incorporate spatially oriented single-site-like catalyticmoieties into ultrahigh-aspect-ratio MOFs.

The word “illustrative” is used herein to mean serving as an example,instance, or illustration. Any aspect or design described herein as“illustrative” is not necessarily to be construed as preferred oradvantageous over other aspects or designs. Further, for the purposes ofthis disclosure and unless otherwise specified, “a” or “an” means “oneor more”.

The foregoing description of illustrative embodiments of the inventionhas been presented for purposes of illustration and of description. Itis not intended to be exhaustive or to limit the invention to theprecise form disclosed, and modifications and variations are possible inlight of the above teachings or may be acquired from practice of theinvention. The embodiments were chosen and described in order to explainthe principles of the invention and as practical applications of theinvention to enable one skilled in the art to utilize the invention invarious embodiments and with various modifications as suited to theparticular use contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto and theirequivalents.

What is claimed is:
 1. A metal-organic framework comprising: inorganicnodes that comprise an octahedral Zr₆ cluster capped by eight μ₃-ligandsand have twelve octahedral edges, wherein the the μ₃-ligands are hydroxoligands, oxo ligands, aquo ligands, or a combination thereof; andorganic linkers connecting the inorganic nodes, the inorganic linkerscomprising 1,3,6,8-tetrakis(p-benzoic acid)pyrene units; wherein eightof the twelve octahedral edges of the inorganic nodes are connected tothe 1,3,6,8-tetrakis(p-benzoic acid)pyrene units.
 2. The metal-organicframework of claim 1, wherein the μ₃-ligands comprise hydroxo ligands.3. A metallated metal-organic framework comprising: a porousmetal-organic framework comprising: inorganic nodes that comprise anoctahedral Zr₆ cluster capped by eight μ₃-ligands and have twelveoctahedral edges, wherein the the μ₃-ligands are hydroxo ligands, oxoligands, aquo ligands, or a combination thereof; and organic linkersconnecting the inorganic nodes, the inorganic linkers comprising1,3,6,8-tetrakis(p-benzoic acid)pyrene units; wherein eight of thetwelve octahedral edges of the inorganic nodes are connected to the1,3,6,8-tetrakis(p-benzoic acid)pyrene units; and a metal film on thesurfaces within the pores of the porous metal-organic framework.
 4. Themetallated metal-organic framework of claim 3, wherein the μ₃-ligandscomprise hydroxo ligands.
 5. The metallated metal-organic framework ofclaim 3, wherein the film comprises zinc.
 6. The metallatedmetal-organic framework of claim 3, wherein the film comprises aluminum.7. A method of catalyzing a reaction, the method comprising exposingchemical reactants to the metallated metal-organic framework of claim 3,whereby the metal film catalyzes a reaction between the chemicalreactants.
 8. The method of claim 7, wherein the reaction is acondensation reaction catalyzed by Lewis acidic sites on the metal film.9. The method of claim 8, wherein the metal film comprises zinc and theLewis acidic sties on the metal film are Zn^(II) sites.
 10. The methodof claim 8, wherein the metal film comprises aluminum and the Lewisacidic sties on the film are Al^(III) sites.
 11. A method of remediatingspecies from a sample comprising the species, the method comprising:exposing the sample to the metallated metal-organic framework of claim3, whereby the species in the sample are adsorbed or absorbed by themetallated metal-organic framework; and removing the metallatedmetal-organic framework and the adsorbed or absorbed species from thesample.
 12. The method of claim 11, wherein the species comprise, metalelements, molecules, or ions.
 13. The method of claim 11, whereinspecies comprise heavy metals.
 14. A metal-organic framework comprising:a porous metal-organic framework comprising: inorganic nodes thatcomprise an octahedral Zr₆ cluster capped by eight μ₃-ligands and havetwelve octahedral edges, wherein the the μ₃-ligands are hydroxo ligands,oxo ligands, aquo ligands, or a combination thereof; and organic linkersconnecting the inorganic nodes, the inorganic linkers comprising1,3,6,8-tetrakis(p-benzoic acid)pyrene units; wherein eight of thetwelve octahedral edges of the inorganic nodes are connected to the1,3,6,8-tetrakis(p-benzoic acid)pyrene units; and an oxide film on thesurfaces within the pores of the porous metal-organic framework.
 15. Themetal-organic framework of claim 14, wherein the oxide film comprises ametal oxide.